The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
In general, a vehicle includes a turbocharger and a supercharger in order to increase engine power. The turbocharger is a device that rotates a turbine using the pressure and thermal energy of exhaust gas generated during the explosion stroke of an engine and rotates an impeller on the same rotary shaft therewith, thereby enabling air introduced through an air cleaner to be sucked into the combustion chamber of the engine for increasing an air filling ratio through the supercharging of the sucked air, and thus achieving an improvement in engine power and a reduction in exhaust gas. In addition, the supercharger is a device that enables air introduced through an air cleaner to be sucked into a combustion chamber, by means of using the power of a motor or an engine, for increasing an air filling ratio through the supercharging of the sucked air, similarly to the turbocharger.
When the turbocharger and the supercharger are mounted and used in the vehicle, engine power may be increased over several dozen % by the increased amount of air in the engine of the same displacement. However, the turbocharger has a turbo lag phenomena in that a smaller quantity of air than that in a naturally aspirated engine flows into the combustion chamber in a low-speed and low-load operating region. In the low-speed and low-load operating region, the energy of exhaust gas is low due to the characteristics of the turbocharger, i.e. the turbocharger brings about a turbo lag.